00 HUMAN PHYSIOLOGY. 



the diminution of excitability near the anode, the anelectrotonic. 

 that now nearest the muscle, being manifested by a less marked 

 contraction than the normal when the nerve is stimulated in this 

 region. Similar conditions exist within the electrodes. Between the 

 electrodes is a neutral point, where the catelectrotonic area merges 

 into the anelectrotonic area. If the current be a strong one, the 

 neutral point approaches the cathode ; if weak, it approaches the 

 anode. 



When a nerve impulse passes along a nerve, the only appreciable 

 effect is a change in its electric condition, there being no change in 

 its temperature, chemic composition, or physical condition. The 

 natural nerve-currents, which are always present in a living nerve as 

 a result of its nutritive activity, in great part disappear during the 

 passage of an impulse, undergoing a negative variation. 



Law of Contraction. If a feeble galvanic current be applied to 

 a recent and excitable nerve, contraction is produced in the muscles 

 only upon the making of the circuit with both the direct and inverse 

 currents. 



If the current be moderate in intensity, the contraction is produced 

 in the muscle, both upon the making and breaking of the circuit, with 

 both the direct and inverse currents. 



If the current be intense, contraction is produced only when the 

 circuit is made with the direct current, and only when it is broken 

 with the inverse current. 



FOODS AND DIETETICS. 



During the functional activity of every organ and tissue of the 

 body the living material of which it is composed the protoplasm 

 undergoes more or less disintegration. Through a series of descend- 

 ing chemic stages it is reduced to a number of simpler compounds, 

 which are of no further value to the body, and which are in conse- 

 quence eliminated by the various eliminating or excretory organs 

 the lungs, kidneys, skin, liver. Among these compounds the more 

 important are carbon dioxid, urea, and uric acid. Many other com- 

 pounds, inorganic as well as organic, are also eliminated in the 

 water discharged from the body, in which they are held in solution. 



